The invention relates to an adhesive tape dispenser with a cutting-off device which has a blade, and to its use for cutting off adhesive tapes without injury.
Roller-type dispensers for rolls of adhesive tape serve the user as a receptacle for storing the rolls of tape themselves and as an application aid when putting them to use. The primary task of an adhesive tape dispenser is the simple, easy and neat cutting to length of strips of adhesive tape in the length required for the intended use. Typical embodiments of dispensers comprise as basic elements a supporting housing, a roll receiving means in the form of a core, a rest for the adhesive tape and a cutting off or tearing off device. A distinction can be drawn between the following basic embodiments:
Dispensers of a usually very compact form (also referred to below as compact dispensers), comprising an open or closed housing, which, in side view, may be, for example, of a round, trapezoidal, rectangular or polygonal shape. For use, the roll of adhesive tape is put onto a usually cylindrical core receiving means, which is integrated approximately centrally in the housing. To the side, the dispenser contains a slit-like outlet gap, from which the adhesive tape is drawn out for cutting to length. The cutting blade by means of which a piece of adhesive tape of the desired length can be cut off is usually located on one side of the outlet slit. The side of the outlet slit opposite the cutting blade is usually intended as a receiving surface for the tacky side of the adhesive tape and is formed in such a way that a piece of self-adhesive tape adhesively fixed thereon can be easily lifted off. An exemplary embodiment of a corresponding dispenser is described in WO 95/23108.
Dispensers in which the housing receiving the roll of adhesive tape and of an open or closed design is spatially separate from the elements comprising the adhesive tape rest and the cutting blade. Corresponding dispensers are in widespread use as hand held dispensers and as desk-top dispensers. With reduced compactness, they offer the advantage that adhesive tape can be removed quickly and simply and one-hand operation is often possible. An exemplary embodiment of a corresponding dispenser is described by U.S. Pat. No. 4,059,210.
Dispensers in which the adhesive tape required can be transferred directly to the substrate, for example via a guide roll which at the same time acts as a pressure-exerting roll and (also referred to below as transfer dispensers). For cutting to length, the pressure-exerting roll has ahead of it a cutting blade or a comparable device by means of which the adhesive tape can be cut off, for example by a slight rotational movement of the dispenser. An exemplary embodiment of a corresponding dispenser is described by WO 96/06790.
For cutting to length a section of adhesive tape of the desired length, a corresponding piece of adhesive tape is unrolled and is cut off with the cutting blade. The form and materials of suitable cutting blades vary. Blades with a serrated cutting edge (blade edge) are used most frequently. In the case of injection-moulded dispensers, the serrated edge may be produced in the injection moulding process itself (see, for example, tesa Film-Abroller [roll dispenser] 55975-87). It is also customary to integrate into the dispenser a metal cutting blade. Among the advantages offered by metal blades in comparison with plastic serrated edges are greater mechanical strength and greater sharpness, so they are more durable and more flexible in use with respect to the materials which can be cut (for example with respect to film thickness or film type). To avoid injuries being caused by accidentally touching the blade edge, for example with the fingers, numerous proposals have been made. For instance, FR 2710331 xe2x80x9cDxc3xa9rouler de ruban adhesifxe2x80x9d [adhesive tape roll dispenser], U.S. Pat. No. 5,022,576 xe2x80x9cLever operated protective cover for a saw tooth-shaped cutterxe2x80x9d, U.S. Pat. No. 5,393,367 xe2x80x9cTape dispenser with a protected cutting devicexe2x80x9d and U.S. Pat. No. 5,456,790 xe2x80x9cTape dispenser with a blade protectorxe2x80x9d describe various forms of protective covers for the cutting blade which can be moved manually or by means of an automatic mechanism, to the greatest extent exclude the possibility of the user being injured by the blade and at the same time serve as a guard to prevent damage to the blade. Examples of adhesive tape dispensers in which the cutting blade is available only when the dispenser is in use are described in JP 080112171 xe2x80x9cTape cutterxe2x80x9d, WO 95/23108 xe2x80x9cDispenser for adhesive tape and the likexe2x80x9d and U.S. Pat. No. 5,456,790 xe2x80x9cTape dispenser with a blade protectorxe2x80x9d.
A disadvantage of dispensers with serrated cutting blades is that self-adhesive films which use backing materials of low tear propagation resistance and low ductility in particular cannot be detached again satisfactorily from many adherend surfaces. This applies in particular to adhesive films which use as a backing highly stretched biaxially oriented films based on it-PP homopolymers, but equally to highly stretched films based on other highly crystalline polyolefins as well as biaxially stretched PETP, to name just a few. When using a dispenser blade with a serrated cutting edge, when a strip of adhesive film is cut off there is an impression of the structure of the teeth on the cut edge of the adhesive tape cut to length. The serrated blade edge and any sharp burr or damage there may be on the blade very often cause extremely fine tears in the cut edges of the adhesive film strips obtained. As a consequence of the impression left of the structure of the teeth and the said extremely fine tears in the cut edges of the adhesive film strip, the attempt by the user of the adhesive tape to detach an adhesively fixed adhesive film strip once again from the adherend surface in one piece very often fails. Rather, adhesive films often tear, starting from the existing cut edges, when it is attempted to detach them again. For the complete removal of an individual adhesive film strip, it is not uncommon for a laborious procedure to be subsequently required to prise the strip off the adherend surface. Difficult to remove remains of an adhesive film, remains of adhesive substance on the adherend surfaced as well as damage to sensitive underlying surfaces consequently cannot be ruled out.
The use of sharp smooth-edged cutting blades makes it possible for the aforementioned self-adhesive films to be detached again satisfactorily, since in this case there is no damage to the cut edges in the form of tears and the smooth form of the blade means that the cut edge is straight. For many applications, a smooth cut edge of the adhesive film is also desired for aesthetic reasons or else is advantageous or necessary for technical reasons, the latter for instance if the adhesive strip is to be used on a document to be photocopied and it is required that there is no or only minimal shadowing on the copies. For instance, DE 29616409 describes an adhesive film roll dispenser which uses commercially available exchangeable razor blades, as a result of which copying defects and soiling of the cutting blade edge do not occur. The tesa-Tischabroller [desk-top dispenser] 6082 uses smooth blades which make possible an absolutely straight cut edge of the adhesive tape to be cut into portions. Adhesive film strips which use a biaxially oriented PP backing, for example tesa-Multi-Film or tesa-Practic-Film, cut to length with the tesa-Tischabroller 6082, can be satisfactorily detached again in virtually all cases. However, injuries to the fingers in particular cannot be ruled out when the aforementioned dispensers are used. U.S. Pat. No. 4,175,685 describes an adhesive tape dispenser which uses a cutting unit containing a razor blade. To protect against injuries, a flexible filament-like material is wound spirally around the blade. The edge of the razor blade is accessible between individual turns of the spiral. A transversely cutting smooth blade, integrated into a blade bar, is used in the tesa-Industrie-Tischabroller [industrial desk-top dispenser] 6080. The special arrangement and orientation of the cutting blade beneath the blade bar to the greatest extent excludes the risk of the user being injured. The blade edge, running obliquely with respect to the plane of the adhesive tape to be cut, at the same time makes it possible for the adhesive tape to be easily cut to length. The tesa-Automat 6056 likewise uses a blade which runs obliquely with respect to the adhesive tape, this blade being electromagnetically activated. The risk of the user being injured by the cutting blade is likewise excluded to the greatest extent.
A disadvantage of the aforementioned adhesive tape dispensers with smooth, straight blade edges of great sharpness is the increased risk of injury at the cutting edges if there is no protective covering and additional manipulations are necessary when putting the adhesive film to use, due to the manual removal or displacing of a protective blade cover. In the case of the aforementioned cutting blades which are exposed by an automatic mechanism when they are put to use, an complex mechanical construction of the adhesive tape dispenser is necessary, which may increase manufacturing costs and the size of the units and may likewise reduce functionality.
It was the object of the invention to provide a remedy here, in particular to provide adhesive tape dispensers with cutting-off devices
which allow the use of cutting blades which are easily accessible with the adhesive tape to be cut off,
in which the use of extremely sharp cutting blades is possible, without there being a significant risk of the user being injured and without complex additional measures for protecting the user having to be integrated, such as for example blade covers or complex mechanical constructions which activate the blade only at the time it is to be used,
which produce a smooth cut edge in the adhesive film, so that it is possible for applied adhesive films to be satisfactorily detached again (in particular adhesive films with a backing film based on biaxially oriented polypropylene),
which allow extremely easily cutting off of adhesive films, in particular with biaxially stretched film backings,
in which the cutting blades are protected to the greatest extent against mechanical damage,
which can be produced at low cost.
This object is achieved by an adhesive tape dispenser which includes a cutting-off device as characterized in more detail in the claims.